I'd start with picking a technology and controller that does what you want.
I've used Z-Wave and LightwaveRF and both have their pros/cons.
There are links to shops/products on my project log here:
http://forums.overclockers.co.uk/showthread.php?t=18578296
I currently have the following all run by apps on my iPhone
Phillips Hue lighting
Sonos music systems
D-link cameras